<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<form action="/login3" method="get">
    <label>
        用户名：<input type="text" name="username"/>
    </label><br>
    <input type="submit" value="提交"/>

</form>
</body>
</html>